PXB4219E Datasheet, PDF (58/290 Pages) Infineon Technologies AG – Interworking Element for 8 E1/T1 Lines

IWE8, V3.4
PXB 4219E, PXB 4220E, PXB 4221E
Operational Description
4.4
AAL Reassembly Functions
When AAL type 0 is enabled in the “AAL Transmit Reference Slot”, the SAR-PDU and
SAR-SDU processing is disabled.
When AAL type 0 is disabled in the “AAL Transmit Reference Slot”, the SAR-PDU
header is processed according to AAL type 1 as defined in ITU-T I.363.1 [31].
For ports configured to AAL mode the following data flow is valid:
The cell transmit processing block is responsible for:
• Port and channel identification
• SNP field check
• SN field check
• SDT pointer detection and verification
• SRTS value extraction
• CAS processing
• Statistics counter event generation
• Insertion of dummy cells at cell loss
• Write to Reassembly Buffer
The octet transmit processing block is responsible for:
• Read octets from Reassembly Buffer
• Handling of Reassembly Buffer Overflow
• Handling of Reassembly Buffer underflow
• Reassembly Buffer initialization to compensate CDV
• Synchronization of SDT structure with port structure
• Statistics counter event generation
4.4.1 Operation
4.4.1.1 Port and Channel Identification
Before an incoming cell is processed, it is determined to which port and channel the cell
is destined. This information is retrieved from the UTOPIA interface (see Chapter 5.2.3).
4.4.1.2 Sequence Number Protection field check
When an un-correctable multi-bit error is detected the Sequence Number (SN) field of
the SAR-PDU header is declared invalid, otherwise the SN field is valid. The function can
be enabled or disabled by the bit “snp_check” in the “AAL Transmit Reference Slot”. If
disabled the SN of all incoming cells are declared valid.
Data Sheet
58
2003-01-20